Unit 4: Cell Communication and Cell Cycle

Learn about the body's systems and how they use cells to signal each other.

Browse slides from the stream 'Body systems.'

Come and test your knowledge with 25 questions!

A look at positive and negative feedback with examples, as well as a review of the cell cycle and its regulation.

Browse slides from the stream 'Cell Communication.'

In this session, Jessica will go into detail about the various methods that cells use in order to communicate with one another. She will provide examples of each type of communication.

In this session, we cover aspects of the endocrine system. We look at how hormones signal, and discuss the differences between the major feedback mechanisms (negative and positive feedback). In addition, we learn that the endocrine system regulates growth, metabolism, sexual development, and homeostasis to allow our bodies to thrive. Furthermore, we review positive and negative feedback examples, such as water level retention, calcium levels, menstruation, and blood sugar regulation. Positive feedback amplifies the stimulus (ex. labor process where the mom’s brain secretes oxytocin to allow for contractions, then the release of prostaglandins, and more oxytocin is secreted as the cycle continues), while negative feedback decreases the stimulus to maintain homeostasis (ex. if the body’s temperature is high, blood vessels dilate and excess heat is sweated off). We end the session with a review of how hormones signal and great ways to study for the class.

Browse slides from the stream 'Endocrine System,' where we cover topics including Systems.

In this lesson, we'll learn about the nervous system, including key components and processes.

Browse slides from the stream 'Nervous System,' where we cover topics including Cellular Processes, and Cell Signaling.

Browse slides from the stream 'Immune System.'

In this lesson, we'll discuss the immune system, including key players and processes.

In this session, we cover mitosis and meiosis. We begin by discussing the purpose (mitosis to replicate SOMATIC cells and meiosis to create GAMETES [sex] cells). We review key vocabulary and then focus on mitosis (to make copies of cells). We then discuss cell cycle regulation (G1 checkpoint, G2 checkpoint, and metaphase checkpoint). We discuss meiosis and follow that with independent assortment (possibility 1 and possibility 2). We discuss random fertilization and sexual versus asexual reproduction. The session ends with FRQ practice.

Browse slides from the stream 'Mitosis & Meiosis,' where we cover topics including DNA & Genetics, Cellular Processes, and Systems.

In this session, we begin by reviewing what we have covered in our previous live sessions. Next, we discuss the non-living signals of plants (and gain a better appreciation of plants). We discuss how cells talk (sending cells, target cells, non-target cells). We show the types of signaling, and discuss phytochromes (pigment that detects light, inactive and active, inside of plants). We cover phototropism using an experiment by Darwin and discuss auxin (hormone responsible for phototropism, leading to cell elongation on the “dark” side of the plant). We review signaling (permeable and impermeable). We discuss photoperiodism (how plants respond to time) and seed germination (gibberellin). We discuss the ripening hormone (ethylene) and gravitropism (negative versus positive gravitropism). We conclude this session with multiple choice practice questions.

Browse slides from the stream 'Abiotic Signaling,' where we cover topics including Systems, Cell Signaling, and Cellular Processes.

In this session, we cover cell signaling, or how cells “talk” (sending, target, non-target cell). We cover the 3 main types of signaling (direct contact, local signaling, long distance signaling). We provide 3 types of examples of long distance signaling (yeast cells [have “genders"], quorum bacteria, and antigen recognition by T cells). We cover the 3 stages of signal transduction and explain the signal phosphorylation. We show how signals are amplified and use a multiple choice question to show how if you can read a graph and be good critical thinker, you can answer the question.

Browse slides from the stream 'Cell Signaling,' where we cover topics including Information, Systems, and Cellular Structure.

The cells in your body communicate in many different ways. Cells must communicate with each other and the environment in order to complete tasks. They communicate through chemical signals. These signals are usually proteins. Multicellular organisms have trillions of cells that communicate in the following ways. 

Transduction is the conversion of a signal into a cellular response. Transduction occurs in one step but the majority of the time it takes multiple changes.

As we talked about earlier, cells communicate and respond to changes in the environment. The environment also has the ability to influence cells in order to elicit a response.

Changes to any structure in the cell cycle can affect the signal transduction pathway. As we talked about earlier, the signal transduction pathway has the ability to alter cellular processes. Specifically, mutations can lead to detrimental effects on later responses. 

Based upon the environment around the organism, the timing, and coordination, there can be either a positive or negative feedback. Organisms use feedback to maintain homeostasis as well as respond to the environment. 

The cell cycle is the sequence of steps prior to cell division. In eukaryotic cells, the cell cycle is highly regulated through the growth and reproduction of cells. The cell cycle consists of 5 phases: interphase (G1, S, and G2), mitosis, and cytokinesis.

Mistakes in duplication can lead to mutations that can lead to cells being abnormal. Because of this, cell cycle checkpoints are done.